refactor(backend): update services and tests

- services/expense_claims.py: update expense claims service
- services/user_agent.py: update user agent service
- tests/test_orchestrator_service.py: update orchestrator service tests
- tests/test_user_agent_service.py: update user agent service tests

server/tests/test_user_agent_service.py

@@ -246,6 +246,36 @@ def test_user_agent_draft_returns_structured_payload() -> None:
         assert response.answer == response.review_payload.body_message
 
 
+def test_user_agent_returns_draft_limit_message_when_save_is_blocked() -> None:
+    session_factory = build_session_factory()
+    with session_factory() as db:
+        ontology = SemanticOntologyService(db).parse(
+            OntologyParseRequest(
+                query="请按当前识别信息保存报销草稿",
+                user_id="pytest",
+            )
+        )
+        response = UserAgentService(db).respond(
+            UserAgentRequest(
+                run_id=ontology.run_id,
+                user_id="pytest",
+                message="请按当前识别信息保存报销草稿",
+                ontology=ontology,
+                context_json={"review_action": "save_draft"},
+                tool_payload={
+                    "draft_limit_reached": True,
+                    "message": "你当前已保存 3 个草稿，请先完成已保存的草稿，才能再次新建草稿。",
+                    "status": "blocked",
+                },
+            )
+        )
+
+        assert (
+            response.answer
+            == "你当前已保存 3 个草稿，请先完成已保存的草稿，才能再次新建草稿。"
+        )
+
+
 def test_user_agent_builds_review_payload_for_multi_document_expense_flow() -> None:
     session_factory = build_session_factory()
     with session_factory() as db: